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A two-dimensional electrophoretic study of serum amyloid A and C-reactive protein in infants and children
C F Bruun1, J C Sanchez, D F Hochstrasser
1Institute of Clinical Medicine, University of Tromsø, Norway. cathrine@fagmed.uit.no
Insights
Serum amyloid A protein (SAA) and C-reactive protein (CRP) levels vary with age in children. SAA is crucial in neonates, suggesting its potential as an infection marker in this group.
Area of Science:
- Biochemistry
- Immunology
- Pediatrics
Background:
- C-reactive protein (CRP) and serum amyloid A protein (SAA) are key acute-phase reactants.
- Understanding their expression patterns in infants and children is crucial for assessing health and disease.
Purpose of the Study:
- To analyze and compare the expression of CRP and SAA isotypes in infants and children.
- To investigate the age-dependent variations and developmental regulation of SAA and CRP.
Main Methods:
- Two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) was employed for protein analysis.
- Densitometry and immunoturbidimetric measurements were used to quantify protein levels and correlate findings.
Main Results:
- Five SAA isotypes were identified, with SAA1alpha being predominant in neonates and both SAA1alpha and SAA2alpha present in children.
- SAA levels were equal to or higher than CRP in over 50% of neonates, while CRP levels were higher in children.
- N-terminally modified forms of SAA were detected across all age groups, indicating independent processing.
Conclusions:
- SAA synthesis is developmentally regulated, but N-terminal processing is independent of developmental factors.
- SAA plays a significant role in neonates, warranting further investigation as a potential infection marker in this population.
Abstract:
Two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) was used to analyze C-reactive - (CRP) and serum amyloid A protein (SAA) in infants and children. Five SAA isotypes were identified. CRP showed vertical streaking, and its optical density values correlated with immunoturbidimetric measurements. As evaluated by densitometry, both proteins showed an age-dependent variation. In more than 50% of the neonates, SAA was present in equal or higher amounts than CRP, and only SAA1alpha could be detected. In children, CRP was expressed in higher amounts than SAA, and both SAA1alpha and SAA2alpha were present. N-terminally modified forms of both isotypes were present regardless of age, including in premature infants. These results suggest that the overall synthesis of the gene products SAA1alpha and SAA2alpha is developmentally regulated, but at the same time that their N-terminal processing occurs independently of developmental factors. The presented data suggest that SAA has an important function in neonates, and that the role of SAA as an infection marker in this population should be investigated further.